The ransomware had already wreaked havoc with more than 200,000 European computers including some from the UK’s National Health Service.

Once ransomware is on a computer – usually after the user clicks a link in a spam email – it locks access to files and requests a fee to unlock it.

The WannaCry campaign has targeted older versions of Windows and asks users to pay US $300 to unlock their computer.

The hackers behind it had made about $60,000 from people paying to unlock their computers.

Tehan says the problem is serious and can cripple businesses so they should thoroughly prepare.

“Small business owners should be pro-active about their cyber security in the wake of this ransomware campaign affecting computers around the world,” he says.
“All businesses should immediately update their Windows operating system with the latest security patches and there are instructions on the ACSC website to do this.

“If your business has been infected you should isolate the affected computer from your network to prevent the software spreading and use backup data to restore information.

“I urge all businesses to visit the Australian Cyber Security Centre (ACSC) website or call 1300 292371 for more information and to contact the ACSC if you have been infected.

“This ransomware attack is a wake-up call to all Australian businesses to regularly backup their data and install the latest security patches.”

Businesses can avoid costly ransomware or other cyber attacks by ensuring their computer systems are regularly updated, back up data often and by educating staff on how to avoid dodgy emails.